The objective of this project is to identify human genes determining slower rates of aging, and then to understand how these genes function. The project is focused on the hypothesis that genetic linkage analyses can be used to test the hypothesis that allelic variance of genetic loci strongly influence the probability of occurrence of two major indicators of slower aging: late fertility in women and longevity. Sibling-pair genetic analysis is the main method used. This study is just under way, although 103 patient samples have been processed by the Core Laboratory for this project. Many elderly subjects have blood drawn in their homes, but some come to the GCRC Outpatient Clinic. The Utah population database, a genealogic database, was used to study fertility and longevity in nearly 9,000 sibships containing individuals born between 1850 and 1900. In sibships selected on the basis of having either a 98-and-a-half-year-old sister or brother as the proband, the risk of non-proband siblings surviving to age 90 was approximately twofold greater than the risk of surviving to 90 in the general population. In sibships identified on the basis of displaying both late fertility in at least one sister and longevity in at least one additional sibling, the chances of living to 90 in the remaining siblings was markedly higher than in the sibships identified only on the basis of having at least one long-lived sibling. These intriguing data support the hypothesis of a genetic basis for longevity.